The Chrome OS "will be offered to users in the fourth quarter," said Sundar Pichai, Google's vice president of product management, during a speech at the Computex electronics exhibition in Taipei.
The statement appears to push back earlier talk of a third-quarter launch for the OS, which is expected to compete with Microsoft's Windows 7 as well as other OSes.
The Chrome Web Store will open at the same time so people can download Web applications that can be installed on the Chrome OS, he added.
"For Chrome OS, we are focused on laptops for this year," he said at a news conference later in the day.
The company designed Chrome OS for clamshell devices with touchpads, keyboards and screens between 10 inches and 12 inches across, he said, clarifying that anything, including netbooks, that fits the hardware specifications will have an easy time gaining Google certification.
Certification by the company is meant to ensure hardware makers create a quality device for users.
Initially, Chrome OS will limit certain customization such as user interfaces that some Taiwanese laptop makers are planning, but over time more customization will be allowed. "So, yes to UIs, but later," he said.